Day off for witches' meeting? (7)

I believe the answer is:

sabbath

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'day off' is the definition.
(day off work)

I don't understand the remainder of the clue.

(Other definitions for sabbath that I've seen before include "Religious day of rest for Jews and Christians" , "Hebrew word for day of rest" , "Day of rest and worship" , "Traditional holy day" , "Jewish rest-day" .)

I've seen this clue in The Guardian.

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